On Feb. 22, NASA Administrator Charles Bolden visited the National Center for Advanced Manufacturing Rapid Prototyping Facility at NASA's Marshall Space Flight Center in Huntsville, Ala., where engineers are using a 3D printing process called "selective laser melting" - seen here being applied to a prototype rocket engine part - to create complex, full-scale rocket-engine parts without welding. The use of 3D printing and prototyping technologies like this one is critical to NASA's development of the Space Launch System, the next-generation rocket that will launch astronauts to more distant destinations than ever before.